CHICAGO, Ill. -- Making his first public remarks since Mitt Romney announced Paul Ryan as his running mate, President Barack Obama gave a double-edged welcome to the new Republican vice presidential nominee, indicating how he seeks to define the new ticket for the remainder of the election.

Speaking to a crowd of young supporters at the Bridgeport Art Center here, Obama said Mitt Romney’s theories of “top-down economics” were apparent in his vice presidential pick of Ryan, the architect of a controversial deficit-reduction budget proposal that includes restructuring Medicare into a "premium support" or voucher system.

“Just yesterday morning, my opponent chose his running mate – the ideological leader of the Republicans in Congress,” he said, seeking to fuse Ryan’s economic views – mostly admired in conservative circles but also viewed by some as radical – with Romney’s.

“My opponent and Congressman Ryan and their allies in Congress, they all believe that if we just get rid of more regulations on big corporations and we give more tax breaks to the wealthiest Americans, it will lead to jobs and prosperity for everybody else. That’s what they’re proposing. That’s where they’ll take us if they win,” he said.

Tying Ryan's provocative budget proposals to former Massachusetts Gov. Romney had already been a popular line of attack for the Obama campaign, but the choice of Ryan as a running mate means that tactic will likely become even more prevalent in coming months.

David Axelrod, a senior adviser to President Obama, summed up the choice to pick Ryan on NBC's Meet the Press: "I think that it clarifies the choice for the American people. And I think it clarifies the choice in a way that is going to be helpful."

The crowd started to boo at the first mention of Ryan but Obama urged them to hold their jeers, stressing that his disagreements with the Republican vice presidential hopeful are policy-based, not personal.

“I want to congratulate Congressman Ryan,” Obama said. “I know him. I welcome him to the race. Congressman Ryan is a decent man; he is a family man.”

Obama’s compliments, however, contained an implicit criticism. The president called Ryan “an articulate spokesman for Governor Romney’s vision. But it’s a vision that I fundamentally disagree with.”

NBC’s Shawna Thomas contributed to this report. Follow her on Twitter.